Without repeating what Innerzone said...

I had a boss in the past whose job involved Meyers-Briggs stuff. She said one of the greatest problems with it is that people don't understand that it should be contextualized. So when you answer, you should be thinking of "me at work" or "me at home" because people really do answer differently for different social contexts. You might want to try it sometime and see if that clarifies anything for you.

I also get a split response to the MB, though. The I and E switch around by mood. When I'm up, I'm an E. When I'm down, I'm an I. But I never really made the connection to mood before - it makes a ton of sense for me, so thanks for that! And I'm 100% consistent on the rest of it - NTJ (strongest on the N and J). But I also find that I score an "I" if I'm thinking about workplace contexts, and an "E" if I'm thinking about informal contexts. So the context part probably plays into it as well.

IZ, I've not tried the Enneagram, but I'll have to do look it up. My mom was pretty into that for awhile and I remember books about it floating around my house when I was a kid.

So, to throw another personality test into the mix... Tried the Big 5 yet? I got an OCEAN the one time I took it: Open to new experiences; Conscientious; Extraverted; Agreeable; and Nervous/high-strung.